President Donald Trump's chief economic adviser Larry Kudlow called comments by Canadian Prime Minister Justin Trudeau at the G7 summit a "diplomatic betrayal".

The director of the National Economic Council was appearing on CNN's "State of the Union" Sunday when he suggested Trudeau should "apologize in the name of the Western allies."

Kudlow was referring to Trudeau's comments in a news conference following diplomatic talks that he disagreed with the Trump administration's decision to impose tariffs on steel and aluminum imports from Canada, the European Union, and Mexico.

Kudlow said Trudeau "stabbed us in the back" and "did a great disservice to the whole G7" with his "amateur political stunt".

"I have made it very clear to the President that it is not something we relish doing, but it something that we absolutely will do," Trudeau said in the news conference. "Canadians, we're polite, we're reasonable, but we also will not be pushed around."

Trump also targeted Trudeau on Twitter this weekend after the talks, saying Trudeau's "false statements" led him to decide not to sign the G7 communique.

Kudlow doubled down on blaming Trudeau in an appearance on CBS' "Face the Nation" later Sunday morning when he said the prime minister "picked a fight" and left Trump no choice but to pull out of the group's communique.

"What's not in good faith is when you leave there, you fly out of there, and the host Canadian prime minister starts taking whacks at you, pot-shots at you — on the eve of this Korean summit," Kudlow said. "President Trump had no alternative, in my opinion."

Kudlow says the G7 nations should have stood behind the US ahead of the North Korea summit

When host Jake Tapper asked what's next for Trump's diplomacy, Kudlow said Trump's response was to set a picture of strength as a leader ahead of his meeting with North Korean leader Kim Jong Un, which is slated to take place this Tuesday in Singapore.

"He is not going to permit any show of weakness on the eve of this trip to negotiate with North Korea, nor should he," Kudlow said on CNN.

When Tapper asked if Trump was planning any payback for Trudeau's comments, Kudlow said he wasn't aware of any further moves.

"I don't know anything about that," Kudlow said. "But President Trump has every right to push back publicly on this Trudeau amateur scheme."

One stunning photograph captured the tensions between the US and other nations at the G7 summit in La Malbaie, Quebec, Canada on June 9, 2018. German Federal Government/Jesco Denzel via Associated Press

Senators push back on Trump's trade actions

Democratic Sen. Dianne Feinstein of California appeared after Kudlow on the same program and called Trump's decision to not sign the communique a "mistake".

"We need to stand with our democratic allies," Feinstein said. "Will there be differences of opinion, will we not like a statement that one or the other makes? Of course. But that doesn't mean you reject what the G-7 stands for and just move out and ignore it."

Sen. John McCain of Arizona also tweeted his disappointment with Trump's decision to ditch the communique on Saturday night.

"To our allies: bipartisan majorities of Americans remain pro-free trade, pro-globalization & supportive of alliances based on 70 years of shared values," the Republican senator said. "Americans stand with you, even if our president doesn't."